Mathematical Modeling of Eddy-Current Loss for a New Induction Heating Device

A new induction heating device is presented in this paper. This device can convert mechanical energy into heat energy by utilizing eddy currents, which are induced by rotating permanent magnets. A mathematical model is established for estimating eddy-current loss of the device. The distribution of induced currents and the resultant magnetic field intensity are considered in the process of modeling the eddy-current loss and so is the mutual influence of the electric field between neighborhood pole projection areas. Particularly, the skin effect is considered by correcting the numerical integral domain of eddy current density, which has great effect on the calculating results. Based on specific examples, the effectiveness and correctness of proposed model are proved by finite element analysis. The results show that the mathematical model can provide important reference for design and structure optimization of the device

Truncated Total Least Squares Method with a Practical Truncation Parameter Choice Scheme for Bioluminescence Tomography Inverse Problem

In bioluminescence tomography (BLT), reconstruction of internal bioluminescent source distribution from the surface optical signals is an ill-posed inverse problem. In real BLT experiment, apart from the measurement noise, the system errors caused by geometry mismatch, numerical discretization, and optical modeling approximations are also inevitable, which may lead to large errors in the reconstruction results. Most regularization techniques such as Tikhonov method only consider measurement noise, whereas the influences of system errors have not been investigated. In this paper, the truncated total least squares method (TTLS) is introduced into BLT reconstruction, in which both system errors and measurement noise are taken into account. Based on the modified generalized cross validation (MGCV) criterion and residual error minimization, a practical parameter-choice scheme referred to as improved GCV (IGCV) is proposed for TTLS. Numerical simulations with different noise levels and physical experiments demonstrate the effectiveness and potential of TTLS combined with IGCV for solving the BLT inverse problem

Efficacy and safety of polymyxin E sulfate in the treatment of critically ill patients with carbapenem-resistant organism infections

ObjectivePolymyxins are currently the last line of defense in the treatment of carbapenem-resistant organisms (CRO). As a kind of polymyxin available for clinical use in China, we aim to explore the efficacy and safety of colistin sulfate (Polymyxin E sulfate, PES) in this study.MethodsThis real-world retrospective study included 119 patients diagnosed with CRO infection and treated with PES for more than 72 h, from May 2020 to July 2022 at West China Hospital. The primary outcome was clinical efficacy at the end of treatment, and secondary outcomes included microbial response, in-hospital mortality and incidence of nephrotoxicity.ResultsThe effective clinical and microbiological responses were 53.8% and 49.1%, respectively. And the in-hospital mortality was 27.7%. Only 9.2% of patients occurred with PES-related nephrotoxicity. Multivariate analysis revealed that duration of PES was an independent predictor of effective therapy, while age-adjusted Charlson comorbidity index (aCCI) and post-treatment PCT(p-PCT) were independent risk factors for poor outcome.ConclusionsPES can be a salvage treatment for CRO-induced infections with favorable efficacy and low nephrotoxicity. The treatment duration of PES, aCCI and p-PCT were factors related to the clinical effectiveness of PES

An animal model of SARS produced by infection of Macaca mulatta with SARS coronavirus.

A new SARS animal model was established by inoculating SARS coronavirus (SARS-CoV) into rhesus macaques (Macaca mulatta) through the nasal cavity. Pathological pulmonary changes were successively detected on days 5-60 after virus inoculation. All eight animals showed a transient fever 2-3 days after inoculation. Immunological, molecular biological, and pathological studies support the establishment of this SARS animal model. Firstly, SARS-CoV-specific IgGs were detected in the sera of macaques from 11 to 60 days after inoculation. Secondly, SARS-CoV RNA could be detected in pharyngeal swab samples using nested RT-PCR in all infected animals from 5 days after virus inoculation. Finally, histopathological changes of interstitial pneumonia were found in the lungs during the 60 days after viral inoculation: these changes were less marked at later time points, indicating that an active healing process together with resolution of an acute inflammatory response was taking place in these animals. This animal model should provide insight into the mechanisms of SARS-CoV-related pulmonary disease and greatly facilitate the development of vaccines and therapeutics against SARS

Genetic variants in novel pathways influence blood pressure and cardiovascular disease risk.

Blood pressure is a heritable trait influenced by several biological pathways and responsive to environmental stimuli. Over one billion people worldwide have hypertension (≥140 mm Hg systolic blood pressure or  ≥90 mm Hg diastolic blood pressure). Even small increments in blood pressure are associated with an increased risk of cardiovascular events. This genome-wide association study of systolic and diastolic blood pressure, which used a multi-stage design in 200,000 individuals of European descent, identified sixteen novel loci: six of these loci contain genes previously known or suspected to regulate blood pressure (GUCY1A3-GUCY1B3, NPR3-C5orf23, ADM, FURIN-FES, GOSR2, GNAS-EDN3); the other ten provide new clues to blood pressure physiology. A genetic risk score based on 29 genome-wide significant variants was associated with hypertension, left ventricular wall thickness, stroke and coronary artery disease, but not kidney disease or kidney function. We also observed associations with blood pressure in East Asian, South Asian and African ancestry individuals. Our findings provide new insights into the genetics and biology of blood pressure, and suggest potential novel therapeutic pathways for cardiovascular disease prevention

Evaluation of procalcitonin, C-reactive protein, interleukin-6 & serum amyloid A as diagnostic biomarkers of bacterial infection in febrile patients

Background & objectives: Early identification of bacterial infection in patients with fever is important for prompt treatment. However, the available parameters such as C-reactive protein (CRP) and leukocyte counts are not very specific. This study was aimed to assess the diagnostic value of procalcitonin (PCT), CRP, interleukin-6 (IL-6) and serum amyloid A (SAA) for bacterial infection in febrile patients. Methods: Serum samples were collected from febrile patients between January and December 2012 and processed for blood cultures. PCT, IL-6, CRP and SAA levels were measured. The patients were divided into three groups according to the final diagnosis: bacteraemia group (group1), bacterial infection with negative blood culture (group 2) and non-bacterial infection group (group 3). Results: There were significant (P<0.05) difference in the levels of PCT, CRP, IL-6 and SAA among the three groups. The PCT levels of patients with g0 ram-positive bacterial infections were lower than g0 ram-negative bacterial infections (0.53 vs 2.13, P < 0.01). The best cut-off value to detect bacterial infections was 0.26 ng/ml for PCT. PCT, CRP, IL-6 and SAA had areas under the curve of 0.804, 0.693, 0.658 and 0.687, respectively. Interpretation & conclusions: Our results showed PCT as a valuable marker of bacterial infections in febrile patients. PCT was superior to CRP, IL-6 or SAA in the early identification of bacterial infection. More prospective and large scale studies are warranted to confirm these findings

Evolution of Microstructure and Elements Distribution of Powder Metallurgy Borated Stainless Steel during Hot Isostatic Pressing

Prepared by powder metallurgy process incorporating atomization and hot isostatic pressing (HIP) sintering at six different temperatures from 600 to 1160 &deg;C, borated stainless steel (BSS) containing boron content of 1.86 wt% was studied. The phase of BSS, relative density of different temperature, microstructure, elemental distribution, and mechanical properties were tested and analyzed. The phases of the alloy were calculated by the Thermo-Calc (2021a, Thermo-Calc Software, Solna, Sweden) and studied by quantitative X-ray diffraction phase analysis. The distributions of boron, chromium, and iron in grains of the alloy were analyzed by scanning electron microscopy and transmission electron microscope. The grain size distributions and average grain sizes were calculated for the boron-containing phases at 900, 1000, 1100, and 1160 &deg;C, as well as the average grain size of the austenite phase at 700 and 1160 &deg;C. After undergoing HIP sintering at 900, 1000, 1100, and 1160 &deg;C, respectively, the tensile strength and ductility of the alloy were tested, and the fracture surfaces were analyzed. It was found that the alloy consisted of two phases (austenite and boron-containing phase) when HIP sintering temperature was higher than 900 &deg;C, and the relative density of the prepared alloys was higher than 99% when HIP temperature was higher than 1000 &deg;C. According to the boron-containing phase grain size distribution and microstructure analysis, the boron-containing phase precipitated both inside the austenite matrix and at the grain boundaries and its growth mechanism was divided into four steps. The tensile strength and elongation of alloy were up to 776 MPa and 19% respectively when the HIP sintering was at 1000 &deg;C

Evolution of Microstructure and Elements Distribution of Powder Metallurgy Borated Stainless Steel during Hot Isostatic Pressing

Prepared by powder metallurgy process incorporating atomization and hot isostatic pressing (HIP) sintering at six different temperatures from 600 to 1160 °C, borated stainless steel (BSS) containing boron content of 1.86 wt% was studied. The phase of BSS, relative density of different temperature, microstructure, elemental distribution, and mechanical properties were tested and analyzed. The phases of the alloy were calculated by the Thermo-Calc (2021a, Thermo-Calc Software, Solna, Sweden) and studied by quantitative X-ray diffraction phase analysis. The distributions of boron, chromium, and iron in grains of the alloy were analyzed by scanning electron microscopy and transmission electron microscope. The grain size distributions and average grain sizes were calculated for the boron-containing phases at 900, 1000, 1100, and 1160 °C, as well as the average grain size of the austenite phase at 700 and 1160 °C. After undergoing HIP sintering at 900, 1000, 1100, and 1160 °C, respectively, the tensile strength and ductility of the alloy were tested, and the fracture surfaces were analyzed. It was found that the alloy consisted of two phases (austenite and boron-containing phase) when HIP sintering temperature was higher than 900 °C, and the relative density of the prepared alloys was higher than 99% when HIP temperature was higher than 1000 °C. According to the boron-containing phase grain size distribution and microstructure analysis, the boron-containing phase precipitated both inside the austenite matrix and at the grain boundaries and its growth mechanism was divided into four steps. The tensile strength and elongation of alloy were up to 776 MPa and 19% respectively when the HIP sintering was at 1000 °C

Effect of Heat Treatment Temperature on Microstructure and Properties of PM Borated Stainless Steel Prepared by Hot Isostatic Pressing

Borated stainless steel (BSS) with a boron content of 1.86% was prepared by a powder metallurgy process incorporating atomization and hot isostatic pressing. After solution quenching at 900–1200 °C, the phase composition of the alloy was studied by quantitative X-ray diffraction phase analysis. The microstructure, fracture morphology, and distributions of boron, chromium, and iron in grains of the alloy were analyzed by field-emission scanning electron microscopy with secondary electron and energy-dispersive spectroscopy. After the coupons were heat treated at different temperatures ranging from 900 to 1200 °C, the strength and plasticity were tested, and the fracture surfaces were analyzed. Undergoing heat treatment at different temperatures, the phases of the alloy were austenite and Fe1.1Cr0.9B0.9 phase. Since the diffusion coefficients of Cr, Fe, and B varied at different temperatures, the distribution of elements in the alloy was not uniform. The alloy with good strength and plasticity can be obtained when the heat treatment temperature of alloy ranged from 1000 to 1150 °C while the tensile strength was about 800 MPa, with the elongation standing about 20%